Appendix Physical Chemistry

Physical Quantities:

    In physical science, we commonly deal with quantities such as pressure, volume, mass, temperature, current, etc. These quantities are known as physical quantities. 
    A physical quantity has two components, namely, numerical value and its unit and is written as, 
Physical quantity Numerical value unit
    Here Physical quantity Newton and its numerical value 5
C.G.S Units and their symbols
C.G.S Units
S.I Units and their symbols
S.I Units
Physical quantity Dimension
Length L
Mass M
Time T

Definition of Base Physical Quantities:

Metre:

    The metre is the length of path traveled by light in vacuum during a time interval 1/299 792 458 of a second.
  • Unit and dimension of Area:
    Area = Length × Length Thus the unit of Area = Unit of Length × Unit of Length
    Unit of Area in C.G.S. System = cm × cm = cm²
    Unit of Area in S.I. System is = m × m = m²
    Dimension of Area = L × L = [L]²
  • Unit and dimension of Volume:
    Volume (V) = Length × Length × Length. Thus the unit of Volume = Length × Length × Length.
    Unit of Area in C.G.S. System = cm × cm × cm = cm³
    Unit of Area in S.I. System is = m × m × m = m³
    Dimension of Area = L × L × L = [L³]
  • Unit and dimension of Density:
    From the definition of Density (d) = Mass/Volume Thus the unit of density = Unit of Mass/Unit of Volume.
    Unit of Area in C.G.S. System = gm/cm³ = gm cm⁻³
    Unit of Area in S.I. System is = Kg/m³ = Kg m⁻³
    Dimension of Area = [M]/[L³] = [M L⁻³]
  • Unit and dimension of Force:
    From the Newton Second Low of Motion, Force = Mass × Acceleration or, Force = Mass × Velocity/Time or, Force = Mass × (Length/Time) /Time
    Here Velocity = Length/Time
    ∴ Force = Mass × (Length/Time²)
    Thus the unit of Force in C.G.S. System, =Unit of Mass × (Unit of Length/Unit of Time²)
    = gm × cm/sec² = gm cm/sec² or, gm cm sec⁻² or, Dyne
    Again in the same way Unit of Force in S.I System, = Kg m/sec² or, Kg m sec⁻² or, Newton
    From the above discussion dimension of Force, = dimension of Mass × dimension of Length/dimension of Time². 
    Thus the dimension of Force = [M L T⁻²]
    Convert 1 newton into dyne:
    1 Newton = Kg m/sec² = (1 Kg× 1 m )/(1 sec)²
    We know that, 1 Kg = 10³ gm and 1 m = 10² cm
    Thus, 1 Newton = (10³gm × 10² cm)/(1 sec)² = 10⁵ gm cm/sec2 = 10⁵ Dyne
  • Unit and dimension of Work:
    From the definition of Work (W) = Force(F) × Displacement(d). Thus, the unit Work = unit of Force × unit of Displacement(d)
    ∴ Unit of Work in C.G.S. System, = (gm cm/sec²) × cm or, gm cm²/sec² or, gm cm²sec⁻² or, erg
    And unit of work in S.I. system = (Kg m/sec²) × m or, Kg m²/sec² or, Kg m²sec⁻² or, Joule
    From the above discussion dimension of Work, = (dimension of Mass × dimension of Length)²)/(dimension of Time²)
    Thus dimension of Work = [ML²T⁻²]
    Convert 1 Joule into erg:
    1 Joule = 1 Kg m²/sec² = (1 Kg × 1 m² )/1 sec²
    We know that, 1 Kg = 10³ gm and 1 m = 10² cm
    Thus, 1 Joule = {10³ gm × (10²)² cm}/1 sec² = 10⁷ gram cm²/sec²
    = 10⁷ erg
  • Unit and dimension of Force:
    The ability to doing work is termed as Energy. Thus, the unit and dimension of energy and work is same.
    Unit of Energy in C.G.S System is erg and S.I. System is Joule
  • Unit and dimension of Pressure:
    From the definition of Pressure (P) = Force/Area Thus the unit of Pressure = Unit of force/Unit of area.
    Unit of Pressure in C.G.S. System = erg/cm² = erg cm⁻²
    Unit of Pressure in S.I. System is = joule/m² = joule m⁻²
    Dimension of Pressure = [M L⁻²]

Physical Quantities, C.G.S. Units and S.I. Units and Dimension of density, force, work, pressure etc. Conservation of 1 Newton to 1 Dyne and 1 Joule to 1 erg

Inorganic Chemistry

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